1. Field of the Invention
The present invention relates to a technology for generating a predicted background image for a currently shot image with the use of images shot in advance under circumference where light source environment and a shooting angle of a camera change and to a technology for detecting an object from the shot image by utilizing the predicted background image.
2. Description of the Prior Art
For object detection using a pan-tilt (PT) camera or the like, a method is effective in which one large panorama image is synthesized from a plurality of shot images of which angles of view are different from each other and image processing of a background difference or the like is performed with the use of the synthesized panorama image as a predicted background image.
As a prior art technique relating to such a predicted background image, for example, Japanese Patent Application Laid Open Publication No. 2002-150264A discloses a method for synthesizing a panorama image in which a motion vector is obtained from camera position, camera posture, and an input image set through an image analysis, a camera parameter is calculated on the basis of the thus obtained motion vector, and images are joined according to the calculated camera parameter. By this method, the respective images can be aligned accurately, so that a predicated background image with less position distortion can be synthesized. Hence, accurate object detection can be performed with the use of this predicted background image.